Portion of staircase



FIG. 1 is a perspective view of a portion of a staircase; and,

FIG. 2 is a top plan view of the portion of a staircase shown in FIG. 1.

The broken lines in the drawings are for illustrative purposes only and form no part of the claimed design. 

I claim the ornamental design for a portion of a staircase, as shown and described. 